Grinding machine



April 20, 194-3. p scucc 2,316,886

GRINDING MACHINE Filed Sept. 29, 1941 2 Sheets-Sheet l F-' IQA.

INVENTOR.

EUGEN/O PASCUCC/ ll TTORNE Y April 20, 1943. E, PAscucc| 2,316,886

GRINDING MACHINE Filed Sept. 29, 1941 2 Sheets-Shet 2 INVENTOR. EUGEN/O PASCUCC/ and the housing for the gears.

Patented Apr. 20, 1943 GRINDING NIACBINE Eugenio Pascucci, Hamilton Township, Mercer County, near Trenton, N. J.

Application September 29, 1941, Serial No. 412,718

3 Claims.

My invention relates particularly to machines for grinding terrazzo, cement or mineral floors, walls, steps and the like but the novel features thereof are adapted for use in machines for sand pap ering or polishing wooden floors or other surfaces.

Grinding machines for mineral floors, as heretofore constructed, are provided with a stone, formed of emery or other grinding material, and secured at its center to a hollow rotatable shaft through which water is passed to aid in the grinding operation. The stone is secured to the shaft by loose pivotal connections which permits the stone to follow generally along the contour of the surface being ground but transmit severe vibration to the rotatable shaft lengthwise thereof. These loose connections also tend to permit the stone to wobble about and increase the vibration and chatter of the stone and shaft and render it difficult to control and direct the movement of the stone over the floor. In fact, vibration of the shaft is so great that it has been necessary heretofore to mount the shaft in bearings which permit the shaft to slide longitudinally with respect to the gears by which the shaft is driven and with respect to the housing within which the gears are located.

Because of the combined longitudinal and rotary movement of the shaft which carries the stone it is practically impossible to provide effective packing between the shaft and the gear housing so as to retain lubricant about the gears and prevent water from entering the gear housing. Moreover it is necessary to provide a sliding key connection between the shaft and the gear by which it is driven in order that the gears may remain in engagement While the shaft moves longitudinally with respect thereto.

For these reasons the shaft, bearings, gears and other elements of the machine are subjected to excessive wear and cannot be properly lubricated and therefore are noisy in operation and must be replaced or repaired frequently.

In accordance with my invention these objections to constructions of the prior art are overcome and a machine provided in which vibration is materially reduced and the shaft which carries the stone is mounted in fixed relation with respect to the gear for driving the shaft It is therefore possible to provide suitable packing to insure proper and continued lubrication of the elements and to exclude water from the gear housing.

These advantages are attained by providing novel yieldable connections between the stone and the hollow rotatable shaft by which it is driven. These connections take up the vibration so that the shaft is not subjected to severe shocks, chatter and vibration and at the same time the stone is continuously and uniformly urged toward the surface to be ground. It is also found that this yielding connection renders the machine much easier to control since the stone may be moved close to pipes, walls or other objects and upon engagement of the edge of the stone therewith the stone yields readily instead of throwing the stone and machine sideways out of control as in prior constructions.

The principal objects of my invention are to decrease the vibration and wear of the shaft and driving connections of grinding machines, to decrease the noise of operation, improve the lubrication of the parts and to provide a machine which is easy to control and operate.

Another object of my invention is to provide a grinding machine with improved means for connecting the stone to the shaft by which it is carried.

A further object of my invention is to provide a grinding machine with a rotatable stone carrying shaft having a gear for driving the shaft which is fixedly secured thereto and adequately lubricated.

Another object of my invention is to provide novel means for packing the shaft by which the stone of a grinding machine is carried.

These and other objects and features of my invention will appear from the following description thereof in which reference is made to the figures of the accompanying drawings.

In the drawings:

Fig. 1 is a side elevation of a typical floor grinding machine embodying my invention,

Fig. 2 is an enlarged vertical sectional view of certain elements of the construction illustrated in Fig. 1,

Fig. 3 is a perspective of the preferred form of connection between the stone and shaft illustrated in Fig. 2, and

Fig. 4 is a vertical sectional view through an alternative form of stone and mounting therefor.

In that form of my invention illustrated in the drawings the grinding machine is provided with a stone 2 rotated by means of a hollow shaft 4 driven by bevelled gears 6 and 8 located in a. gear housing It. The gear 6 is fixedly secured to the shaft 4 whereas the gear 8 is connected toa motor driven shaft l2 located in the shaft tube 14 and driven by motor it through gears l8 and 20 in the gear casing 22.

The motor is supported on a platform 24 mounted on wheels 26 and is controlled by suitable switches within a switch box 28. The upper platform 38 upon which the switch box 28 is mounted also supports a water container 32 from which water is passed through a tube 34 to' the central opening 36 in the rotatable shaft 4. In this way water is supplied through the hollow shaft 4 to the surface being ground by the stone 2.

In order to relieve the shaft 4 of vibration and thereby permit the use of improved bearings, packings and driving connections, resilient means such as the spring 38 are located between the shaft 4 and the stone 2 and serve to urge the stone away from the shaft so as to take up vibration between the stone and shaft. The spring 38 is '4 by a key 42 andthe set screw '44-. The upper portion of the attaching member engages a shoulder 48 on the shaft 4, whereas the lower portion ofthe attaching member is provided with spaced downwardly extending projections 48 threaded'to receive screws fgll for securing a'flexible ri'ng'liZ to the attaching member 48.

The flexible ring 52 is formed of fibrous ma- 'terial, fiber-rubber composition or the like'and extends about the spring 38. A connector member 54 is'located below the flexible ring 52 and provided with upwardly projecting bosses 56 secured to 'the ring 52 at points-spaced fromgthe downwardly extending projections 48 on the i attaching member so as to provide a yieldablecohnection between the attaching member and connector member.

The connector member '55 is providedwith a downwardly extending centering portion 58 having a T-headed projection 60 adaptedto-enter'the opening 62 in a mounting plate 84 secured to 'the stone 2 by shellacor other bonding material. V'Ihe'stone is removably' secured to the connector member by'rotation to cause the ends of the1 T headed projection 6b to extendbeneath the shoulders-66 of the opening'EZ in the mounting plate '64. The ends'ofthe'projections tfi-engage'pins 68 carried by the mounting platev 64 so as to prevent relative rotation of'the'm'ounting plate and connector member during operation.

The upperend of the spring 38 bears against the central'portion of the attaching member'lw,

whereas the lower end of thespring is located about the shoulder 18 on the upper face'of'the V connector member 55 and thesprin'gis held un- "der compression so that the stone '2'isyieldably urged away from the shaft 4. 7

By connecting the attaching member and'the mounting member to the flexible ring 52 at spaced points about the same and using the spring 38 in combination therewith the'stone is permitted to move axially with respect to the shaft so as to take up vibration and is also yieldably movable with respect to the shaft so as'to provide pivotal connection which permits the stone 'to'be. moved up'against pipes or walls'to' grind the surface close thereto. Upon engagement' of the edge of the stone with'the'pipe or wallthe stone yields readily and does not throw the head of the grinding machine away or out of control as do prior machines in which the stone is pivotally secured to its shaft.

This yielding connection between the stone and shaft also renders it possible to mount the shaft 4 within the gear housing 10 so as to be rotatable with respect to the housing while being held against longitudinal movement with respect thereto. It is therefore :possible to provide suitable packing between the shaft 4 and the bottom cover 12 of the gear housing 10 so as to retain lubricant in the housing and about the gears 6 and 8. It is also possible to provide packing between the shaft 4 and the upper cover -14 of the gear housing to prevent water from passing down about the shaft into the gear housing. Moreover the yieldable connection between the stone and shaft renders it possible to secure the gear 6 fixedly to the shaft 4 and thereby eliminate one of the mos'tserious sources of wear in devices 'of the prior art.

The preferred type-of mounting shown in the drawings includes lower bearings '16 engaging the collar 18 on shaft igand held in place by the lower housing cover 12 while having a force fit with the lower portion of the housing 1-0. The lower housing cover also supports the paking 19 which prevents the escape of lubricant from the gear housing and-is oompressed'bythe cover attaching screws 80.

The upper portion of the shaft 4 is provided with a -bearing 82 which engages the shoulder-84 onthe shaft and has a force .fit at 86 'with the upper portionof tlie housing If). The upper end of the shaft 4 extends intoa recess 88 within the upper housing --cover 1'4. In this way the shaft 4 is mounted in the housing I'll andheld against longitudinal movement with "respect thereto while'the gear 6 is fixedly-secured to the shaft 4 by means of the key Qfi an'ddshld {in position to properly engage the motor driven gear 6 for rotating the 'shaft;4.

In order to exclude-water from thegear housing a felt packing member '92 is located'within the topof the recess 83 in the upper-"housing cover and bears at its lower *ends against the -packing cover 96. The packing is thus yieldably urged against the shaft and the inner *wallhf the recess "88. The packings filandfl aremounted on a supporting ring Hidand roller bearings [62 arelocated between the supporting ringl'fifl and the shoulder 1 14 on' the shaft y so'as to "reduce the-wear upon the-packing The upperp tion of the recess 88 above'the packingfdlgbi formed with an opening, j as indicated, at lfift o drain water from the recess and' thereby furtlrer aid in preventing leakage of w aterinto thegear housing along the shaft. j

I In order} to manipula'te the grinding machine and guide the-stone over the'surface tobeground a handle I 86 is secured-to the upper portion'of the housingcover '74 by'meansof 'thescrew Hi8 engaging the threads I It!) in the upper portion of the housing cover {14 and havinga head i if H bearing against the upper face of thehan'dle. Thescrew l as is provided with a central passage l l 4 which communicates; with the centraljopene ing 36 in the shaft 4 through the massage I I5 in the center of the upperhousing'cover 14. I'n

this way water may be passed to the central opening in the shaft 35 from the tube 32 and thence through the central opening I H3 in the connector member 54 to the space within the stone 2 and the surface to be ground.

When it is desired to change the position of 115 handle 5% with respect to the gear housing iii and tube I l it is only necessary to loosen the screw I68 and turn the handle to the desired position and then tighten the screw again. Simiiarly, if it is desired to use the machine in grinding walls or the risers for stairs, the set screw i2$ carried by the shank I22 of the gear housing It! may be loosened to permit the housing and shaft 8 to be rotated with respect to the tube 54 through which the motor driven shaft I2 extends. The bearing I24 between the gear 8 and the shank I22 of the gear housing permits such rotation of the housing and also serves to support and position the gear 8 accurately with respect to the gear housing so as to properly engage the gear 6 on the shaft 4.

While I have shown and described one form of means for removably securing and centering the stone with respect to the connector member as shown in Figs. 2 and 3, the stone may be attached to the shaft in various ways and other types of stones or grinding elements may be employed. Thus, as shown in Fig. 4 the stone I36 may be provided with an inwardly extending rim 32 and may be removably secured and positioned on the connector member I35 by means of a threaded element I36 having a head I33 which bears against the lower face of the rim I32 on the stone while the threads I46 on the neck of the element #36 engage complementary threads on the connector member I35; to draw the stone into engagement with the lower face of the connector memoer.

he element i3 is provided with a central opening I42 which communicates with the opening in the hollow rotatable shaft so as to conduct water from the shaft to the surface being ground.

Other types of stones and other forms of attaching elements may obviously be employed for performing special grinding operations or for use in adapting the invention for sandpapering or polishing operation on wood or other materials.

Similarly, the form, construction and type of grinding machine and gears, bearings and-driving elements employed may be varied considerably without departing from the spirit of my invention. In view thereof the forms of my invention shown in the drawings and herein described should be understood as only illustrative of my invention since they are not intended to limit the scope of the following claims.

I claim:

1. A grinding machine having a stone, a shaft for rotating said stone and located in axial alignment therewith and axially yieldable means for connecting the stone to the shaft comprising, an attaching member fixedly secured to the shaft, a connector member fixedly secured to said stone, a flexible member connected to said attaching member and to said connector member, and a compressible spring located between said attaching member and connector member urging said members apart so as to take up vibration between the shaft and stone when the machine is in operation.

2. A grinding machine having a stone, a shaft for rotating said stone and located in axial alignment therewith and axially yieldable means for connecting the stone to the shaft comprising, an attaching member fixedly secured to the shaft, a connector member fixedly secured to said stone, a flexible member in the form of a ring connected at spaced points to said attaching member and connected at intervening points to said connector member, and a compressible spring located between said attaching member and connector member and urging said members apart to take up vibration between said shaft and stone when the machine is in operation.

3. A grinding machine having a stone, a shaft for rotating said stone and located in axial alignment therewith and axially yieldable means for connecting the stone to the shaft comprising, an attaching member fixedly secured to the shaft, a connector member fixedly secured to said stone, a flexible member in the form of a ring connected at spaced points to said attaching member and connected at intervening points to said connector member, and a compressible spring located between said attaching member and said mounting member and in axial alignment with said shaft urging said members apart to take up vibration between said shaft and stone when the machine is in operation.

EUGEN'IO PASCUCCI. 

